Choke valve operating mechanism



Dec 31, 1940.

L. E. PERRINE 2,226,580

CHOKE VALVE OPERATING MECHANISM Original Filed March 11, 1935 3 Sheets-Sheet l l'muentor attorney A Dec. 31, 1940. L. E, p m 1 2,226,580

CHOKE VALVE OPERATING MECHANISM Original Filed March 11, 1935 3 Sheets-Sheet 2 Znwcutor oCeslw G 7mm Dec. 31, 1940. v PERRlNE 2,226,580

CHOKE VALVE OPERATING MECHANISM Original Filed March 11, 1935 3 Sheets-Sheet 3 Patented Dec. 31, 19.40

- UNITED STATES PATENT OFFICE azzasso. 1 a

CHOKEYhIfVE OPERATING MECHANISM Lester a. Perrine,Detroit, Mich, assignor to General Motors Corporation, Detroit, Mich a cor-.

poration of Delaware Application March 11, 1935, serial N... 10,512 v Renewed February 1', 1940 19.0mm. (c1. 123-119) This invention relates-to mechanisms for facilitating starting and insuring proper and continuous operation of an internal combustion engine "when its temperature is belovi'that at which it is I designed to operate.

The invention resides in mechanisms for auto-; matical l'y maintaining the choke valve of the carburetor of "an internal combustion engine so adjusted as to insure that the combustible mixture supplied to the engine by the carburetor, while the engine is being started and whem its temperature is belowthat at which it is designed to operate, will contain'the optimumpronortionsof' and 6, of fuel and air. The mechanisms are improve-' ments over that disclosed in my copending application, Serial No. 602,267, filed March 31, 1982, principally, in that there is incorporated therein, to insure more accurate adjustment of the choke valve, means whereby the position of the choke valve is affected by the pressure within the induction system of the engine on the engineside of the carburetor, as well as by the temperature of thqe'ngine' or some part thereof. a

To insure, after the enginefhas been started, that it willat all times receive sufficient combustible mixture to insure proper and continuous eperationsthereof without making it, necessary at y ti to supply to the engine while it is idling more combustible mixture than is necessary to insure proper and continuous operation thereof, there is. preferably employed in conjunction with the mechanism referred to in the next preceding paragraph, mechanism whereby the extent to which the throttle valve of the carburetor. of the engine may be closed is rendered dependent upon the temperature of the engine or some part thereof. The latter. mechanism is, however, claimed,

' not in this application, but in my copending application, Serial No. 618,225, filed June 20, 1932,

of which this application is, in part, a,continuation.

Fbr a better understanding of the nature and the objects of the present invention, reference is made to the following specification in which there are described the preferred embodiments of my invention which are illustrated in the accompanying drawings: 1

In the accompanying tirawingsL 50 Figure 1 is a view in which there is ventlon isembodied instaliedon an internal combustion engine. I Figure 2 is a top plan view of the mechanism shown in Figure 1 with the cover removed.

wr'a cover 20 which is preferably made of the same shown, mainly in elevation, mechanism in which my in- Figure 3 is a section taken Figure 2. I

Figure 4 is a section taken Figure 2. I

t Figure 5 is a perspective view of an element of the mechanism shown in Figures 1 and 2 for lim-. iting the closing movement of the throttle valve of the carburetor shown in Figure 1.

Figure 6 isa fragmentary view, correspon V .to Figure 3, of a modified form of the mechanism shownin the preceding figures.

' Figure 7 is a view, corresponding to Figures 3 another modified form of the mechanism shown in Figures 1 to 5.

on the line 3-3 of on the line H of Figure 8 is a view, corresponding to Figures 3,

Sand 7, of still another modified form of the mechanism shown in Figures 1 to 5.

Figure 9 is a view, in which there is shown, partly-in elevation and partlyin' section, another embodiment of the invention illustrated in the 50 preceding figures.

In Figure 1 of .the' drawings, there is shown part of the induction system of an internal combustion engine which includes a carburetor l0, into which air is drawn through the conduit in and from which combustible mixture is discharged through the conduit l2, and amanifold l3 through which the combustible mixture discharged from the conduit I2 is conducted to the intake ports of the cylinders, of the engine. .Within the conduit I! on the shaft ,there is mounted a throttle valve I! of the butterfly type and within the conduit ii on the shaft 16, there is 1 mounted a choke valve I! of the butterfly type which is notable only in this, that,"as shownin 85 the drawing, the portion thereof which moves in- .wardly as the valve open's is of greater area than" 'the portion on the opposite side of the' shaft l6 and, consequently, that flow of air into the carburetqr will tend to open it. 40

The embodiment of my invention which is shown in Figures 1 to 5 and the modified forms thereof which are shown in Figures 7', and 8 include a generally receptacular body II which is I seated onand secured by means 'of screws is to the intake manifold ii. The open side of the body, which is preferably made of brass or some other non-magnetic material, is closed by material. 60

In the opposite side walls of the body it, ad-

jacent one end, there are formed bearings 21 in which there is journaled a shaft 22 which extends through the body. On one end of the shaft 22,- without the body,- there is fixed an arm II which is connected by a link 24 to an arm 25 which is fixed on the shaft I 6 on which the choke valve ll is mounted. The opposite end of the shaft 22 extends into a cup-shaped housing 21 which is adjustably secured by a clamp 29 to an extension of the adjacent bearing 2|. Within the cupshaped housing 21, there is located a thermosensitive bimetallic coil spring26 whose outer end is secured to the housing and whose inner end is secured to the end of the shaft 22 which is located within the housing.

Within the body l8, between the shaft 22 and the end of the body farthest from the shaft, there is located a U-shaped permanent magnet 33 which is adjustably clamped by a screw 35 and a plate 36 to a boss 31 which is formed on the inside of the body. To the shaft 22, within the.

lies the poles of the magnet 33.

On the outer side of the end wall of the body l8 farthest from the shaft 22, there is formed a hollow boss 38 into which there extends the closed end of an expansible and contractible metal bellows 39. on the open outer end of the bellows 39, there is formed a flange 49 which is seated on the outer end of the boss 38. The outer end of the bellows is closed by and the bellows is secured to the boss through a plate 4| which'is seated on the flange 49 and secured to the boss 39. The interior of the bellows is connected to the interior of the intake manifold l3 by communicating bores 42, 43 and 43 in the plate 4|, the body 18 and the upper wall of the intake manifold.- To the closed inner end of I the bellows 39, there is connected a short rod 45 which extends into the interior of the body It through an opening 46 in the end wall thereof. The end of the rod 45 which is located within the interior of the body I9 is pivotally connected to an L-shaped lever 41 at the junction of its arms 48 and 59. Through the shorter arm 48 of the lever 41 whichextends upwardly from its 'Eiunction with the longer arm 59 extends a pin 49 which is carried bythe body l8 and serves as a fulcrum for the lever. The longer arm 50 of the lever 41 extends approximately horizontally from its junction with the shorter arm 48 to a point near the distant end wall of the body i8 and at its extremity is pivotally connected by a pin 5| to the lower end of a link 52. The upper end of the link 52 is pivotally connected by a pin 53 to the keeper 29 above the shaft 22 and on engine to which the drawings relate, the thermosensitive element 26 is, as shown in Figures 2 and 4, located in such clos'e juxtaposition to the exhaust manifold 54 of the engine that it is affected by the heat radiated therefrom. It will, of

course, be understood that, in engines in which Y the arrangement of the intake and exhaust manifolds differs from that illustrated in the drawings, it may be found desirable, in order so to locate the thermo-sensitive elements that they will be affected by the heat radiated from the exhaust manifolds, to mount the mechanisms on parts of the engines other than the intake manifolds, and, moreover, if it be so desired, the mechanisms may be so mounted that the thermosensitive elements will be affected by the heat radiated from parts of the engines other; than the exhaust manifolds.

The thermo-sensitive element 26 is so constructed and arranged that, as its temperature rises, it tends to rotate the shaft 22 in a counterclockwise direction when it is viewed as shown in Figures 1 and 3 and to open the choke valve I1, that, as its temperature falls, it tends to rotate the shaft 22 in a clockwise direction and to close the choke valve and that, when its temperature falls below a predetermined value (e. g., 70 F. to R), if unresisted, it will maintain the choke valve in its fully closed position. From what is said in the next preceding sentence, it will be apparent that the thermo-sensitive element 26, when its temperature is below a predetermined value, tends to maintain the choke valve in its fully closed position and, when its temperature equals or exceeds this value, tends to regulate the position of the choke valve in accordance with its temperature and, since the thermo-sensitive element is affected by the temperature of the exhaust manifold 54, in accordance with the temperature of the exhaust manifold. Moreover, it will be noted thatthe attraction of the magnet 33 for the arm 32 of the keeper 29 tends to prevent rotation of the shaft 22in a counterclockwise direction and, therefore, to maintain the choke valve in its closed position.

When an engine on which the mechanism shown in Figures 1 to 5 and hereinbefore described is installed is not operating, the positions of the parts of the mechanism will depend upon the temperature of the exhaust manifold of the engine.- If the engine is sufl'iciently heated, the thermo-sensitive element 26 will maintain the choke valve ll partially or fully open and the arm 32 of the keeper 29 out of the effective field of attraction of the magnet 33. Under these conditions, the position of the choke valve will, while the engine is being started, be controlled entirely by the thermo-sensitive element 26, the volume of air which is flowing through the conduit ii and the suction within the intake manifold l3 which tends to contract the bellows 39 and,- through it, the rod 95, the lever 41, the link 52, the shaft 22, the arm 23, the link 24 and the arm 25, to open the choke valve.

If, however, when the engine is not operating, it

becomes sufficiently cold, the thermo-sensitive element 26 will move the choke valve sufliciently toward its closed position to bring the arm 32 of the keeper 29 into the effective field of attraction of magnet 33 and the arm 32 of the keeper 29. Under the conditions described in the preceding portion of this paragraph, it is obvious that, while the engine is not operating, the position of the choke valve I? will dependpartly'upon the temperature of the thermo-sensitive element 26 and partly the keeper 29 and the tendency of the thermosensitive element 26 to maintain the choke valve in its closedposition. Consequently, since under the conditions in which the arm 32 of the keeper 29 is located within the eflective field of attraction of the magnet, the latter dominates the-thermosensitive element 26 in determining the position of the choke valve, the position-of the choke valve will under the conditions under consideration be determined by the magnet until such time as the flow of air through theconduit ll, plus the suction within the intake manifold l3 becomes sufficient to overcome the attractive force of the magnet for the arm 32 of the keeper 29, plus the tendency, if any, of the thermo-sen'sitive element 26 to maintain the arm 32 of the keeper 29 in the efiective .fleld of attraction of the magnet. When the. flow of air through the conduit ll, plus the suction within the intake manifold l3becomes sufficient to overcome the attractive force of the magnet for the arm 32 of the keeper 29, plus the tendency, if any, of the theijmo-sensitive element 26 to maintain the arm 32 of the keeper 29 within the effective field of attraction of the magnet,

the arm 32 will be moved out of the effective field of attraction of the magnet and, thereafter,

until conditions again become such as to bring the arm 32 of keeper back into the effective field of attraction of the magnet, the position of the choke valvewill depend entirely upon the temperature of the thermo-sensitive element 26, the fiow of air through. the conduit II and the suction within the intake manifold l3.

Since the ratio of fuel to air in the combustible mixture which an internal combustion engine requires for most satisfactory operation is, inpart, a function of the pressure in the induction system of the engine on the engine side of the car- ,buretor, the choke valve adjusting mechanism shown in Figures 1 1:05 is capable'of maintaining the ratio of fuel to air in the eombustiblemixture supplied to the engine more nearly at its optimum value under the several conditions of operation of the engine than is the mechanism disclosed in my previously mentioned application, serial No. 602,267, sincewhen the mechanism shown in Figuresl to 5 is employed, both .the interval during which the position of the choke valve is determined by the magnet and the position of the choke valve after the arm 62 of the keeper 29 has been moved out of the effective field of attraction of the magnet are affected by the pressure within the intake manifold as well as by the temperature of the engine and the flew of air through the conduit ll.

partially open 'when the throttle valve is opened to a predetermined extent, there is preferably provided in conjunction with the mechanism hereinbefore described means whereby the arm32 of the keeper 29 will be moved out of the effective held of attraction of the magnet 33 when the throttle valve has been opened to apredetermined In these hearings, there is journaled a shaft 56 on which, within the body l6, there is formed a cam surface ilwhich is adapted to be brought into engagement with the arm 3| of the keeper 29 to open the choke valve to a predetermined extent when the shafthas been rotated through a predetermined angle. 'I'ointerconnect the shaft 55 with the throttle valve l5 so that the angular position of the shaft will be determined by the position of the throttle valve, there is fixed to one end of the shaft 55 an arm 56 which is interconnected through a link so, a bell crank 66 and a link 6| 1 to an arm 62 which is fixed to the shaft I on which the throttle valve I5 is mounted. It will be ap arent from a consideration of the structure descr bed in the preceding portion of this paragraph that when the throttle valve I5 is opened toapredetermined extent, the cam surface 51 on the shaft 55 will engage the arm 3| of the keeper 29, rotate it in a counter-clockwise direction and positively partially open the choke valve.

To insure, after the engine has been started,

that the throttle valve l5 will not be closed to such an extent as to prevent 'under any conditions suflicient "combustible mixture to insure proper 1 and continuous operation of the engine being supplied to the cylinders of the engine, without making it necessary at any time to supply to the engine while it is idling more combustible mixture than is necessary to insure proper and continuous operation thereof, there is provided in conjunction with the hereinbefore described mechanism, mechanism whereby the extent to which the throttle valve may be closed is rendered dependent upon the temperature of the engine or some part there-- other arm 65 of the lever 62 terminates above a pin 66 which is fixed to the side of the body 16 on which the thermo-sensitive element 26 is located. On the pin 66, there is rotatably mounted a sleeve 61 on whose cylindoidal wall, directly below the end of an adjusting screw 66 carried by the arm 65 of the lever 62, there is formed a cam-like projection 69. On the outer end of the sleeve 61, there is formed a housing 16 in which there is located a bimetallic thermo-sensitive coil spring 1| whose outer and inner ends are fixed, respectively, to the the body l6 tends to rotate the'lever 62 in a counter-clockwise direction; when it is viewed as shown in Figure 1, and to maintain the car 64 in contact with the upper surface of the arm 58. When the engine'is operating at any speed greater than idle, the spring 12 maintains the screw 66 out of contact with the cam 69 and prevents .it interfering with rotation of the element 61-16 on the pin 66.

It will be noted that when the mechanism un- I der consideration is installed on an engine as To insure that the choke valve will be at least shown in, the drawings, the thermo-sensitive element 1| is so located that it is afiected by the heat radiated from the, exhaust manifold and is so constructed and arranged that as its temperature tact with the portion of the cam 69 most distantfrom the axis of the sleeve 61; when the throttle valve I5 is moved toward its closed position, the

arm 58 is moved into engagement with the ear 64 on the lever 83 and causes the lever 63 to rotate in a clockwise direction, when it is viewed as shown inFigure 1, until the screw 68 engages the cam 88 which functions to limit the movement of the throttle valve toward its closed position. From What has been said in the preceding portion of this paragraph, it will be apparent that the cam 69 will i closed to, such an extent as to prevent suiflcient combustible mixtureto insure proper and continuous'opera't-ion of the engine being supplied to the cylinders thereof and that under no condition, when the screw 68 is in contact with the cam, will any more combustible mixture than is necessary to insure proper and continuous'operation of the engine be supplied to the cylinders thereof.

While, since in the form shown herein the thermo-sensitive element ll is not sufliciently powerful to rotate the element 87-18 on the pin 66 when the screw 88 is in contact with the cam 69, the thermo-sensitiveelement will not function to open the throttle valve and, consequently, to facilitate starting of the engine, it will be necessary to open the throttle valve slightly by other means such as the hand throttle control, the accelerator pedal or an interconnection between the throttle valve and the self-starter: it is, of course,- possible to make the thermo-sensitive element ll sufiiciently powerful that it will open the throttle valve to the extent necessary to facilitate starting.

The mechanism shown in Figure fi difiers from that shown in Figures 1 to only in the means through which the force exerted by the suction within the intake manifold is transmitted to the link 52. In the mechanism shown in Figure 6, this means includes a hollow boss I3 whose location is similar to that of the boss 38 and a cover It between which are clamped the outer edges ofa flexible diaphragm I5 whose' central portion is clamped between two plates I8 and II. A screw 78 which extends through the cover I4 engages the outer plate 11 at a point above the center of the diaphragm I5. From the inner plate I8,

there projects an arm I9 which extends into the 5 interior of the body I8 through a vertical guide slot 80. The extremity of the arm I9 which is located within the body I8 is connected to the link 52 by a pivot 8|. I4 and the diaphragm I5 is connected to the interior of the intake manifold I3 by communicating bores 82, 83 and 44 in the cover I, the body l8 and the upper wall of the intake manifold l3.

It will be apparent from a consideration of the structure described in the preceding portion of this paragraph that the suction within the intake manifold I3 will tend to flex the diaphragm I5 to the right when it is viewed as shown in Figure 6, and, consequently, to rock the element 'II-I8-I9 about its fulcrum I8 from the position in which i it is shown in solid lines to that in which it is shown in dot-and-dash lines and to move the choke valve to its open position.

The mechanism shown in Figure '7 differs from that shown in Figures 1 to 5 only in that there is included in the former the thermo-sensitive element designated by the reference character 84. This thermo-sensitiveelement includes a bimetallic thermo-sensitive strip 85 of which one end is seated on and secured by a screw 86 to a boss 81 The space enclosed by the cover formedon the upper surface of the arm 32 of the .keeper 29. The opposite end of the strip 85 carries a pin 88 which projects into an opening 89 which extends vertically through the arm 32 di-- rectly above one of the poles of the magnet 33.

' The strip '85 is, of course, affected by the heat raperature falls. When the temperature of the engine on which the mechanism is installed is below a predetermined value, the strip 85, of course, maintains the lower end of the pin 88 at or above the level of the lower surface of thearm 32 of the keeper 29 and, consequently, the thermo-sensitive element 84, does not affect the operation of the mechanism. However, when the temperature of the engine rises to a value which exceeds the mentioned predetermined value, the pin 88 moves through the opening 88 to a position in which it can engage the pole of the magnet 33 with which it is associated and, consequently, prevents the arm 32 of the keeper 28 from moving within or re-, maining within a predetermined distance of the magnet 33. "This distance varies inversely with the extent by which the temperature of the engine exceeds the mentioned predetermined value until the strip 85 engages the upper surface of the arm 32 of the keeper 29 since the distance which the pin 88 projects below the lower surface of the arm 32 varies in this manner. The pin 88 is preferably made of such length that, when the strip 85 engages the upper surface of the arm 32, it prevents the arm 32 from moving within or remaining within the efiective field of attraction of the magnet 33.

temperature of the engine exceeds a predetermined value. The presence in the mechanism of the thermo-sensitive element 84 is decidedly efficacious in that, by reducing the interval during which the choke valve is held tightly closed during starting operations when the engine is hot, it serves to prevent overchoking under these conditions, and, by preventing the choke valve from becoming or remaining tightly closed at any time when the engine is hot, it reduces the likelihood of the engine being stalled as a result of flooding.

The mechanism shown in Figure'8 differs from that shown in Figures 1 to 5 only in that there is included therein a bimetallic thermo-sensitive strip 90 one of whose ends is secured by a screw 9i'to the body i 8 adjacent the free end of the arm .32 of the keeper 29. The strip 90 is, of course, affected by the heat radiated from the engine on which the mechanism is installed and is so constructed and arranged that when its temperature is below a predetermined value its free end stays out of the path of movement of the arm 32 of the keeper 29 and when its temperature exceeds this predetermined value its free end moves into the path of the arm 32 and prevents it moving into the effective field of attraction of the magnet 33. It will be apparent that, while in general, the strip 90 and the parts associated with it have the same function and operate in the same manner as the thermo-sensitive element 84, the former cannot unseat the arm 32 of the keeper 29 from the magnet 33 or serve as a variable limit to the approach of the arm 92 to the magnet 93 but functionseither not at all or.v

to prevent the arm 32 approaching within a fixed distance of the magnet 33 when the temperature of the engine exceeds a definite predetermined value. a

, \stantaneously What is we in the 1m clause ofithenext preceding sentence is, of course, sub-v Ject to the qualification that while in either of the In Figure 9 of the drawings, the reference character 92 indicates the intake manifold of an internal combustion engine. Although it is not shown, it is to be assumed that there is connected to the intake manifold 92 a carburetor similar to that shown in Figure 1 and that the rod 93 shown in Figure 9 is connected.to the choke valve of a plate 95. The plate '95 is secured to the manifold by screws 99 and constitutes the b0dy-of the embodiment of my'invention which is illustrated in Figure 9.

On the under surface of the plate 95 the intake manifold 92 and are spaced longitudinally thereof. In a slot 99 in the boss 91, there is seated one end of a bimetallic thermo-sensitive strip I99. The other end of the strip I99 extends into a bore I9I in the boss 99 and abuts against a set screw I92 which is threaded into the bore.

Through the plate 95 midway between the bosses 91 and 99 extends an opening I93, which is sealed by a flexible diaphragm I94. Screws I95 clamp the edges of the diaphragm I94 bethere are formed two bosses 91 and 99 which project intotween the plate 95 and an annular member I99 which surrounds the opening I93. On the upper, surface of the annular member I99, there are formed ears'lill to which one end of a lever I99 pin H2. The hole in the diaphragm I94 through which the rod I I I extends is sealed and the rod is secured to the diaphragm by discs II! between the pressiif'in the intake manifold 92 falls orthe temperature rises, the diaphragm I 94 and the.

thermo-sensitive strip I99 tend to fiex downwardly and open the choke valve which is connected to the rod, and when the pressure in the intake manifold rises or the temperature falls the diaphragm and the thermo-sensitive element tend to fiex upwardly and close the choke valve. However, it is to be noted that the thermo-sensitive strip I99 differs from the theme-sensitive element 29 in two important respects, via, (1)

that it is located within the intake manifold in-' and is, therefore, affected by the temperature of the combustible mixture travelling from the carburetor to the cylinders of the en ine rather than stead of in juxtaposition to the exhaust manifold by the temperature of the exhaust manifold and (2) that it is a two position or .snap. type device, that is to say a device which moves instantaneously from one tothe other of the two positions in which it is shown in the drawing and does not occupy any intermediate position except intwo positions illustrated in the drawings the thermo-sensitive strip I99 is capable of function-- ing within limits as a pring without shifting to the other-position.

It will, of course, be understood that, if desired, a balanced instead of an unbalanced choke valve may be employed in conjunction with the mechanisms herein disclosed.

Although I have shown and described preferred embodiments of my invention, it is to be understood that this has been done by way of example and not by way of limitation and that the scope of my invention is to be determined only by the appended claims. P

I claim:

"1. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, meansxfor resisting theinitial movement of the choke valve from its closed toward its open position, and a member responsive to engine operating conditions and a thermally actuated member of which both -are capable of adjusting the choke valve so connected to the first specifled means that they may apply; thereto a force,

which tends to overcome the resistance offered by it to the initial movement of the choke valve from its closed toward its open position and thereafter regulate the position of valve.

2. In an internal combustion engine, .a carburetor in which there is incorporated a choke valve which is so unbalanced that flow of air into the carburetor 'tends to open. it, a member in which thereis provided mpassage which connects the carburetor with a cylinder of the engine, means for resisting'the initial movement of the choke valve from its closed toward its open position, and

so. v

the choke means for adjusting the choke valve which includes'a member responsive to pressure conditions within the mentioned passage and a thermally actuated member of which each isv so connected to the first specified means that it may apply theretoa force which tends to overcome the resistance offered by it to the initial movement of the' choke valve from its "closed toward its open position.

- 3. In an internal combustion engina a carburetor in which there is incorporated'a choke valve,

a member responsive to engine operating conditions and a' thermally actuated member of which 1 both are capableofadiusting the choke ,valve, means for resisting theinitial movement of the choke valve from its closed toward its open position, and means for varying the resistive eflect of the last specified-means in accordance withchangesin temperature.

4.-In an internal combustion engine, a carburetor in which there is incbrporated a choke valve which is so unbalanced that flow of air into the 'carburetor tends to open it, a member in whichthere is provided a e which connects the carburetor with a cylinder of thepengine, means which extends through the recess and is journalled in the walls of the body, and a'magnet and an armature located within the recess in the body and secured one to the shaft and the other to the body.

6. In an internal combustion engine, a carburetor in which there is incorporated a choke valve and operating mechanism for the choke valve in which there is included a body in which there is provided a recess, a shaft which extends through the recess and is journalled in walls of the body, pressure and thermally actuated elements carried by the body and connected to the shaft, and

means for releasably holding the shaft against 15 rotation located within the recess.

'7. In an internal combustion engine, a carburetor in which there is incorporated a choke valve and operating mechanism for the choke valve in which there is included a body in which there is pro ided a recess, a shaft which extends through therecess and is journalled in walls of the body, a

thermally actuated element connected to the shaft and to the body, a pressure actuated element located within a recess in the body and connected to the shaft, and means for releasably holding the shaft against rotation located within the recess;

8. In carburetor choke valve latching mechanism, a magnet and an ar'mtaure of which one is movable toward and away from the other, and a thermallyactuated element which is carried by one of the magnet and armature and limits-the approach of one toward the other.

9. Means for releasably holding the choke valve of a carburetor which includes a magnet, an armature which is movable toward and away from the magnet, and a thermally actuated element which is carried by the armature and limits the approach thereof toward the magnet.

10. Means for releasably holding the choke valve of a carburetor which includes a. magnet and an armature of which one is movable toward and away from the other, and a thermally actuated element which isfixedly mounted with respect to one of the magnet and the armature and limits thgapproach of one toward the other.

11. In carburetor choke valve latching mechanism, a magnet, an armature which is movable toward and away from the magnet, and a thermally actuated element which is fixedly mounted with respect to the magnet and arrests the approach of the armature toward it. I

12. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a member in which there is a passage which connects the carburetor-with a cylinder of the engine, a member responsive to pressure variations within the mentioned passage connected to the choke valve so that it tends to move the choke valve toward its open position when the pressure within the mentioned passage falls, and means, including a magnet and an armature, which op- Doses movement of the choke valve toward its open position by the last specified member and, is eifective while the engine is operatingunder its own power. H

13. In" an internal combustion engine, a carburetor in which there is incorporated a 'choke valve which is so arranged,that the flow of air into the carburetor tends to open ,it, a member in which there isa passage which connects the carburetor with a cylinder. of the engine, a member responsive to pressure variations within the mentioned passage connected to the choke valve so that it tends to move the choke valvotoward its the choke valve toward its open position by thelast specified member. and is effective while the engine is operating under its own 'power..

14. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a member in which there is a passage which connects the carburetor with a cylinder of the engine, a thermally actuated element associated with the choke valve, means, including a magnet and an armature, which tends to hold the choke valve closed and is effective while the engine is operating under its own power, and a member responsive to pressure variations within the mentioned passage connected to the choke valve so that it tends to move the choke valve toward its open position when the pressure within the mentioned passage falls, and, thereafter, in conjunction with the thermally actuated element to regulate the position of the choke valve.

15. In an internal combustion engine, a carburetor in which there is incorporated a choke valve which is so arranged that the flow of air into the carburetor tends to open it, a member in which there is a passage which connects the carburetor with a cylinder of the engine, a thermally actuated element associated with the choke valve, means, including a magnet and an armature, which tends to hold the choke valve closed and is effective while the engine is operating under its own power, and a member responsive to pressure variations within the mentioned passage connected to the choke valve so that it, in conjunction with the flow of air into the carburetor, tends to move the choke valve toward its open position when the pressure within the mentioned passage falls and, thereafter, in conjunction with the thermally actuated element, to regulate the position of the choke valve.

16. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, means for resisting the initial movement of the chokevalve from its closed toward its open position, a thermally actuated member and a member responsive to changes in speed of the engine connected to the choke valve and the first-specified means so that they may apply to the latter a force which tends to overcome it and, thereafter, regulate the position of the choke valve. 17. In an internal combustion engine, a carburetor in which there is incorporated a choke valve, a member responsive to changes in speed of the engine connected to the choke valve so that it may move the choke valve toward its open position, and means, including a magnet and an armature, which opposes movement of the choke valve toward its open position by. the specified member ,and is effective while the engine 'is op- ,erating under its own power.

18. In an internal combustion engine, a carburetor, a valve for regulating the ratio offuel to air in the combustible mixture supplied to the engine by the carburetor, a housing which consistsv engine by the carburetor, a housing which consists of a body anda. cover. a shaft Journaled in the body and operatively connected to the valve,

a bellows disposed within the housing with its open end clamped between the cover and the body and its closed end operetivelyconnected to the shaft, and means thmuzh which fluid may be admitted to and withdrawn from the interior of the bellows through the body and the cover to,-

extend and contract the bellows.

LESTER E. PERRINE.' 

